Technological Field
The present invention relates to a fixing member, a fixing apparatus, and an image forming apparatus. More specifically, the present invention relates to a fixing member, a fixing apparatus, and an image forming apparatus capable of enhancing durability.
Description of the Related art
An electrophotographic image forming apparatus includes: a multi function peripheral (MFP) having a scanner function, a facsimile function, a copying function, a printer function, a data communication function, and a server function; a facsimile machine; a copying machine; and a printer.
An image forming apparatus generally forms an image on a sheet by the following method. An image forming apparatus forms an electrostatic latent image on an image carrier and develops the electrostatic latent image using a developing device to form a toner image. Next, the image forming apparatus transfers the toner image to the sheet, and fixes the toner image onto the sheet by the fixing apparatus. In addition, a certain image forming apparatus forms a toner image on a photoconductor, transfers the toner image to an intermediate transfer belt using a primary transfer roller, and performs secondary transfer of the toner image on the intermediate transfer belt onto a sheet using a secondary transfer roller.
In recent years, in order to achieve energy saving of the image forming apparatus, there is a demand for reduction in the heat capacity of the fixing apparatus. With the fixing apparatus having a small heat capacity, it is possible to rapidly heat up to a target temperature at the time of warm-up while suppressing the power consumption by suppressing the preheating of the fixing apparatus at the time of standby, leading to reduction of the warm-up time.
A fixing apparatus having a small heat capacity is smaller in size and thinner than a fixing apparatus having a large heat capacity. Therefore, a fixing apparatus having a small heat capacity has few heat channels that allow heat to move between a sheet passage part and the sheet non-passage part, making it difficult to allow heat transfer on the heating member from the sheet non-passage part to the sheet passage part (heat transfer in the axial direction of the heating member). This lead to a problem that the temperature of the sheet non-passage part is likely to rise in continuous fixing of small size sheets, deteriorating fixing property and uniformity of the image.
In order to solve the above problem, techniques of enhancing thermal conductivity in the axial direction of the heating member by providing a graphite layer in the heating member are disclosed in JP 2002-6662 A, JP 2001-159418 A (JP 4166914 B2), JP 2014-153659 A, JP 2005-24725 A, and JP 2003-255733 A, for example.
JP 2002-6662 A discloses a fixing belt including a fixing belt base material layer, a fixing belt anisotropic graphite layer, and a fixing belt release layer.
JP 2001-159418 A (JP 4166914 B2) discloses a pressing member in which a crystallized graphite layer is pasted on an elastic layer with an adhesive. In this pressing member, the crystallized graphite layer is formed with a plurality of sheets, with each of the plurality of sheets being arranged on a roller-shaped pressing member spaced from each other.
JP 2014-153659 A discloses a fixing member having a base material, an elastic layer provided on the base material, and a surface layer provided on the elastic layer. At least one of the base material and the elastic layer includes a first filler having a plurality of acicular projections and a second filler having a non-acicular structure. The surface of the first filler is covered with a graphite layer.
JP 2005-24725 A discloses a fixing rotating body including a plurality of wires coated with a low thermal conductivity member around a high thermal conductivity member formed of copper wire being stacked in parallel to the axial direction of the fixing rotating body, with a layer having thermal conductivity anisotropy being arranged between the fixing rotating body base material and the surface layer.
JP 2003-255733 A discloses a fixing apparatus that allows a roller-like member having a graphite layer on an outer circumferential surface thereof to come in contact with an outer circumferential surface of the fixing member or an outer circumferential surface of the pressing member.
In a case where an adhesive is used for fixing the graphite layer as in JP 2001-159418 A (JP 4166914 B2), there is a problem of low adhesiveness of the adhesive and low durability of the fixing member. That is, the fixing member using the adhesive for fixing the graphite layer is likely to allow the graphite layer to be uplifted against the adhesive strength of the adhesive over time, leading to generation of a portion not fixed by the adhesive in the graphite layer. This leads to generation of cracks in the graphite layer starting from the unfixed portion of the graphite layer, causing a phenomenon of breakage. This phenomenon is remarkable particularly in a case where a silicone adhesive or the like is used as an adhesive.